166321421 has 16 divisors (see below), whose sum is σ = 211858560. Its totient is φ = 127111680.

The previous prime is 166321381. The next prime is 166321427. The reversal of 166321421 is 124123661.

It is a cyclic number.

It is not a de Polignac number, because 166321421 - 2¹⁸ = 166059277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166321427) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34520 + ... + 39041.

It is an arithmetic number, because the mean of its divisors is an integer number (13241160).

Almost surely, 2^166321421 is an apocalyptic number.

It is an amenable number.

166321421 is a deficient number, since it is larger than the sum of its proper divisors (45537139).

166321421 is a wasteful number, since it uses less digits than its factorization.

166321421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73604.

The product of its digits is 1728, while the sum is 26.

The square root of 166321421 is about 12896.5662484244. The cubic root of 166321421 is about 549.9409534408.

The spelling of 166321421 in words is "one hundred sixty-six million, three hundred twenty-one thousand, four hundred twenty-one".